This may not be the best or most efficient – or even practical – way of generating power, but it sure is interesting. Here’s a link to an Instructable where the person turns a speaker into…well…a generator. Since I haven’t tried this first hand I find myself wondering if the power produced by putting the “generator” speaker in front of the same sized powered speaker – i.e. the one playing the music – would create a comparable amount of electricity. I’m guessing that’s not necessarily the case, but if it is then I would think that it might be possible to hook up several “generator’ speakers and put them in front of one powered speaker and create multiple times the electricity used. I think I have to test this out myself….